One paradox of advertising comes from a powerful inverse relationship between age and money. The people most likely to be swayed by most commercials are impressionable children (who have no money). Meanwhile, it's incredibly difficult to persuade adults (who have all the money) to break from habit and buy a new product.

A new study from the Journal of Consumer Researchfinds a clever loophole in this paradox. People hold onto a deep fondness for brands, like Kellogg's cereal and other foods with friendly mascots, that they were exposed to as children. The consumer brain is a bag of concrete mix before a person turns 13: Anything you can slip in the soft blend is likely to harden, along with our neural networks, by the time we become a money-spending adult. This Concrete-Mix theory of habit formation was behind efforts to ban cigarette ads targeting young people.

In four separate studies, researchers tested subjects' attitudes for Tony the Tiger (the mascot for Kellogg’s Frosted Flakes), Play-Doh Pete, Cocoa Puffs, Fruit Loops, and other brands that clogged Nickelodeon commercials and Sports Illustrated for Kids pages—if my experience is any indication. People asked to judge the healthiness of these cereals and foods showed inexplicably warm feelings towards not only the characters but also the nutrition value of their favorite foods as kids.

"This research is the first to hypothesize and test a model that explains how childhood exposure to advertising can have effects on product evaluation that persist into adulthood," the authors wrote. They found that, although people tend to be highly critical of promises made in advertisements, they're more likely to positively evaluate a product they learned to love as a child. It's as if their mushy, impressionable child brain returns to block their ability to think like a full-grown adult.

One limitation of the research, which the authors are honest enough to admit, is that it's not quite clear what effect is being measured. The fact that childhood exposure to advertising can have effects later in life has helped argue for characters like Smokey the Bear to promote fire safety, Woodsy the Owl to discourage littering, and McGruff the Crime Dog to fight crime. These are all clear efforts to inculcate habits during the soft-concrete period of a person's brain. But what if what was really being measured in these studies is as simple as plain old nostalgia? Telling a room full of researchers "oh yeah, Frosted Flakes! I love that stuff" is different from actually going to the grocery store to buy fillets, but catching a glimpse of the cereal aisle and stocking up on Fruit Loops for dinner instead. From my unempirical observations of people's lives, it seems to me that nobody does that. Remembering Fruit Loops fondly might be utterly harmless.

But the study still provides more ammunition for the idea that advertising to children is qualitatively different from advertising to adults. If you want to break a country's bad habits—from smoking tobacco to eating crap—best to start young.